Hi Counter
Hi Counter

Sleep Counter

Calculate the best bedtime or wake-up time based on 90-minute sleep cycles. Optimise your sleep schedule for better rest and more energy.

Select a Time

Choose your target wake-up or bedtime above, and we'll calculate the best times based on natural 90-minute sleep cycles.

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How to Use

1

Choose Mode

Select whether you want to find the best bedtime or wake-up time based on your schedule.

2

Set Your Time

Enter your desired wake-up time or bedtime. We factor in 14 minutes to fall asleep.

3

Pick the Best Option

Choose from 6 suggestions. The \"Best\" badge marks the option with the most sleep cycles.

About This Tool

Calculate the best bedtime or wake-up time based on 90-minute sleep cycles. Optimise your sleep schedule for better rest and more energy.

Wake up feeling refreshed by aligning your sleep schedule with natural 90-minute sleep cycles. Our calculator finds the optimal bedtime or wake-up time so you never wake up mid-cycle again.

All data is stored locally in your browser and never uploaded to any server. No registration required.

90-Minute Cycle Science

Calculations are based on the natural 90-minute sleep cycle so you wake up between cycles, not mid-cycle.

Dual Mode — Wake Up or Fall Asleep

Choose whether you want to find the ideal bedtime or the best wake-up time based on your schedule.

Fall-Asleep Adjustment

A built-in 14-minute buffer accounts for the average time it takes to fall asleep, keeping your cycles accurate.

Learn More

1

Better Wake-Up Timing — Set your alarm for the end of a sleep cycle so you wake up feeling refreshed instead of groggy.

2

Shift Work Scheduling — Quickly find the best sleep window when your work hours change from day to night.

3

Jet Lag Recovery — Adjust your bedtime gradually across time zones by calculating optimal sleep and wake times.

Frequently Asked Questions

Authoritative Sources

Standards and research behind this tool, from official specifications to peer-reviewed studies.

Everyday health tracking works best in small, countable units. The US National Academies' Dietary Reference Intakes set general guidance for daily water, potassium, and sodium needs, around which hydration trackers are designed. Step counting, sleep hours, and weekly habit streaks follow the same principle that behavior scientist BJ Fogg teaches: tiny, measurable actions repeated daily are more durable than ambitious goals. Counters make those units visible without an account or an app.

National Academies - DRI for Water and Electrolytes

The US National Academies' Dietary Reference Intakes for water, potassium, sodium, chloride, and sulfate.

www.nap.edu

BJ Fogg - Behavior Model

Stanford behavior scientist BJ Fogg's model of how prompts, ability, and motivation combine to create habits.

behaviormodel.org